Among children 1 to 5 years of age, daily high-dose administration of vitamin D did not reduce overall wintertime upper respiratory tract infections, according to a study published by JAMA.
Viral upper respiratory tract infections are the most common infectious illnesses of childhood. Both observational and clinical trial data have suggested a link between low levels of serum 25-hydroxyvitamin D and increased rates of respiratory tract infections. Whether winter supplementation of vitamin D reduces the risk among children is unknown. Jonathon L. Maguire, MD, MSc, of the University of Toronto, and colleagues randomly assigned children ages 1 through 5 years to receive 2,000 IU/d of vitamin D oral supplementation (high-dose group; n=349) or 400 IU/d (standard-dose group; n=354) for a minimum of four months between September and May.
The average number of laboratory-confirmed (based on parent-collected nasal swabs) upper respiratory tract infections per child were 1.05 for the high-dose group and 1.03 for the standard-dose group. There was also no significant difference in the median time to the first laboratory-confirmed infection: 3.95 months for the high-dose group vs 3.29 months for the standard-dose group, or number of parent-reported upper respiratory tract illnesses between groups (625 for high-dose vs 600 for standard-dose groups).
"These findings do not support the routine use of high-dose vitamin D supplementation in children for the prevention of viral upper respiratory tract infections," the authors write.
A limitation of the study was that children may have had upper respiratory tract infections without swabs being submitted.
Source: Jama Network Journals